Transmission

Abstract

A transmission includes a gear shift set including a shift gear and a switching mechanism, and another gear shift set including a shift gear and a switching mechanism. At a side face of the lower shift gear, dogs are provided to protrude. The switching mechanism includes a first ring configured to rotate integrally with a shaft, a second ring configured to rotate integrally with the first ring, and an elastic member connecting the first ring and the second ring. The first ring includes first projection portions, and a first abutment portion allowing a shift member to abut thereon. The second ring includes second projection portions, and a second abutment portion allowing the shift member to abut thereon.

What is claimed is: 
     
       1. A transmission comprising:
 a shift gear configured to be rotatably attached to a shaft, the shift gear including a plurality of dogs provided to protrude at a side face of the shift gear; and 
 a switching mechanism provided for the shift gear, the switching mechanism being configured to switch between a state in which the shift gear and the shaft rotate integrally and a state in which the shift gear and the shaft do not rotate integrally, the switching mechanism including a first ring, a second ring, an elastic member and a shift member, 
 the first ring being configured to rotate integrally with the shaft, the first ring including a first projection portion, a communication portion and a first abutment portion, the first projection portion having a shape extending toward the shift gear in an axis direction of the shaft, the communication portion having a shape extending in the axis direction, the first abutment portion being provided on a side opposite to the shift gear in the axis direction, and the first abutment portion allowing the shift member to abut on the first abutment portion, 
 the second ring being configured to rotate integrally with the first ring, the second ring being disposed on the side opposite to the shift gear in the axis direction relative to the first ring, the second ring including a second projection portion and a second abutment portion, the second projection portion having a shape extending toward the shift gear in the axis direction, the second projection portion being disposed to extend through an inside of the communication portion of the first ring, and the second abutment portion being provided on a side that is the same as the shift gear in the axis direction, and the second abutment portion allowing the shift member to abut on the second abutment portion, and 
 the shift member being configured to move the first ring in a direction closer to the shift gear, the first projection portion engaging with a dog from among the plurality of dogs, the second projection portion being disposed together with the first projection portion between two of the dogs, and when the shift member moves the second ring in a direction away from the shift gear, the second projection portion being configured to come out from between the two of the dogs while the first projection portion engages with the dog, 
 the elastic member being configured to connect the first ring and the second ring, and the elastic member providing a biasing force making a distance in the axis direction between the first ring and the second ring have a fixed value to the first ring and the second ring using an elastic resilient force of the elastic member, and 
 the shift member being configured to provide a force in the axis direction to the first ring and the second ring. 
 
     
     
       2. The transmission according to  claim 1 , wherein
 the shift gear and the switching mechanism make up a gear shift set, the transmission includes at least two gear shift sets, the gear shift sets include a gear shift set including at least a lower shift gear, the gear shift set including at least the lower shift gear includes a plurality of dogs provided to protrude at a side face of the shift gear, the first projection portion has a shape extending toward the lower shift gear in the axis direction, the first abutment portion is provided on a side opposite to the lower shift gear in the axis direction, the first abutment portion allows the shift member to abut on the first abutment portion, the second ring is disposed on the side opposite to the lower shift gear relative to the first ring, the second abutment portion is provided on a side that is the same as the lower shift gear in the axis direction, the second abutment portion allows the shift member to abut on the second abutment portion, and the shift member moves the first ring in a direction closer to the lower shift gear and the first projection portion engages with a dog from among the plurality of dogs, and when the shift member moves the second ring in a direction away from the lower shift gear, the second projection portion is configured to come out from between two of the dogs while the first projection portion engages with the dog. 
 
     
     
       3. The transmission according to  claim 2 , wherein
 motive power from an engine is transmitted to the switching mechanism via the shift gear, the first projection portion includes an inclined surface, and the inclined surface extends further toward a rear side in a rotation direction of the first projection portion as further away from a side face of the first ring in a part on a front side in the rotation direction of the first projection portion. 
 
     
     
       4. The transmission according to  claim 2 , wherein
 motive power from an engine is transmitted to the shift gear via the switching mechanism, the first projection portion includes an inclined surface, and the inclined surface extends further toward a front side in a rotation direction of the first projection portion as further away from a side face of the first ring in a part on a rear side in the rotation direction of the first projection portion. 
 
     
     
       5. The transmission according to  claim 2 , wherein
 the first ring includes a first side wall extending in a radial direction, the second ring includes a second side wall extending in the radial direction, the elastic member includes a pair of holding portions and a connection portion, the pair of holding portions is configured to hold the first side wall and the second side wall between the pair of holding portions from outside in the axis direction, the connection portion is provided on an inner side in the radial direction of the pair of holding portions, and the connection portion is configured to connect end portions of the pair of holding portions. 
 
     
     
       6. The transmission according to  claim 5 , wherein
 the first side wall includes the first abutment portion, 
 the first abutment portion includes a surface of the first side wall, the surface of the first side wall being positioned on the side opposite to the lower shift gear in the axis direction, and the shift member abuts on the surface of the first side wall, 
 the second side wall includes the second abutment portion, and 
 the second abutment portion includes a surface of the second side wall, the surface of the second side wall being positioned on the side that is the same as the lower shift gear in the axis direction, and the shift member abuts on the surface of the second side wall. 
 
     
     
       7. The transmission according to  claim 5 , wherein
 the first ring includes a third ring and a fourth ring, the third ring and the fourth ring are joined to each other, the third ring includes the first projection portion, and the fourth ring includes the first side wall, and 
 the second ring includes a fifth ring and a sixth ring, the fifth ring and the sixth ring are joined to each other, the fifth ring includes the second projection portion, and the sixth ring includes the second side wall.